Three interrelated themes are to be pursued. 1. An attempt will be made to directly assess the effect of activating the hepatic osmosensitive and sodium sensitive systems on cells in the supra-optic nucleus and adjacent area. The question is the extent to which the anti-diuretic hormone (or vasopressin) system is sensitive to visceral and central receptors. 2. While there is considerable knowledge of the connections between hypothalamus and the brain stem autonomic system, little is known of the functional significance of these pathways. One particular experiment will be to locate hypothalamic and brain stem areas containing iontophoretically identified glucoreceptors. An attempt will be made to study the inputs from gustatory and visceral receptors onto these central glucoreceptors. This will give us some information about the neural substrates of energy regulation and how they code energy related signals. In addition, the central connections of these systems will be studied concentrating on electrophysiological investigations of the connection of the paraventricular nucleus with the dorsal vagal complex. 3. Behavioral studies are planned to look closely at the conditions under which glucose administration either suppresses, paradoxically enhances, or has no effect on food intake. Some variables to be looked at are rate of infusion and the route of entry of glucose. The role of visceral autonomic nervous system, the endocrine system and metabolic pathways will be looked at to find underlying mechanisms for the effects observed.